Generally, in the sample analyzer for aspirating the sample such as blood, and flowing the aspirated sample through a flow path to a flow cell and measuring the same, the flow path used for the measurement is cleaned after the measurement to prevent the component such as blood cells from remaining on the flow path, and influencing the measurement result of the next sample (carry over). In particular, normally, the body fluid such as cerebrospinal fluid, pleural effusion, and the like barely contain cells, and thus the measurement result greatly fluctuates if the component is remaining in the flow path even slightly when measuring such body fluid. Thus, when measuring body fluid it is very important to reduce the carry-over. The technique for reducing the carry-over of when measuring the body fluid is proposed by U.S. Patent Application Publication No. 2008/0187990.
The sample analyzer displays a message urging the blank check measurement on a screen to notify that the measurement result of the next body fluid sample may be influenced if the measurement result of body fluid prior measured is greater than or equal to a predetermined value. When the user instructs the execution of the blank check measurement according to such message, the measurement is carried out using a sample blank that does not contain the body fluid, and whether or not the cells of a predetermined value or greater is counted in the background is determined.
In the sample analyzer described in U.S. Patent Application Publication No. 2008/0187990, the necessity of the blank check measurement is determined in accordance with whether or not the measurement result of prior measured body fluid is greater than or equal to a predetermined value. This is because the flow path is assumed to be sufficiently washed and background noise is assumed to be sufficiently reduced by the washing after the measurement if the measurement result is smaller than the predetermined value.
However, some careful users may perform the blank check measurement each time after the sample measurement and following washing is completed irrespective of the measurement result of the sample measured prior in order to check that the flow path is sufficiently washed. If it is confirmed that the flow path is sufficiently cleaned, next body fluid sample is measured. In order to perform such operation, the operation to instruct the blank check measurement is required each time after the measurement of the body fluid sample.